1. Field of the Invention
The invention relates in general to methods and devices for a clutch with multiple spring systems and, particularly, embodiments of the present invention relate to clutches wherein multiple spring systems with many common components are provided for clutch activation systems, and more particularly motorcycle clutches wherein one of a multiplicity of spring systems may be selected from common components to provide a preferred “feel” or other characteristic for the operation of a clutch.
2. Description of the Prior Art
Mechanical clutches are widely used in power transmissions systems between motors or engines and transmissions or other applications. Air, land, and sea vehicles, agricultural and grounds maintenance implements, construction equipment, stationary systems, and the like, all require the use of some type of clutch to disengage the engine from the application. Certain clutches, and particularly conventional motorcycle clutches, comprise a stack of friction discs and steel plates sandwiched between a generally axially fixed clutch hub and an axially moveable pressure plate. In the engaged position the friction disks and steel plates are forced together and rotate together so that power is transmitted through the clutch. In the disengaged position the disks and plates are slightly separated and do not rotate together, so power is not transmitted through the clutch.
Conventional spring biased pressure plates are generally spring biased into the engaged mode by either compression springs or a diaphragm spring. Conventional pressure plates generally can not accommodate both spring systems either when used concurrently or alternatively. Clutch control members are typically actuated to disengage the pressure plate from the stack of friction discs and steel plates. Disengagement typically involves moving the pressure plate axially against the force of the spring bias. The disengagement force must be sufficient to overcome the force of the spring bias.
The nature of the spring that serves to bias the pressure plate determines the “feel” or behavior of the clutch during engagement and disengagement. Compression springs resist disengaging the clutch with a force that increases progressively as the pressure plate moves towards full disengagement. The force is generally greatest in the fully disengaged configuration. A diaphragm spring (sometimes described as a bellville or disk spring) resists disengaging the pressure plate until the spring substantially flattens, at which point the force diminishes abruptly and substantially, so that little force is required to hold the clutch in the fully disengaged configuration. Upon engagement, the compression spring biased pressure plate systems tend to engage slowly and smoothly with some clutch slippage as the engagement phase of the cycle progresses. Diaphragm spring biased pressure plate systems tend to go very quickly from full disengagement to full engagement with little slippage.
When a clutch is required, for example, to function between a high horsepower motor (for example, over 80 horsepower) and a transmission, the force of the required spring bias may become so great that the clutch controls require some augmentation, such as hydraulic assistance. Such augmented systems may be configured and adjusted to mask the inherent “feel” or behavior of a particular system, but at substantial cost in complexity, reliability, maintenance and initial price.
Some clutch users, particularly motorcycle riders, from time to time wish to change the “feel” or behavior of the clutch. This had previously involved considerable expense, because the pressure plate, spring, and spring confinement components all needed to be changed. In general, it had previously been impossible to tailor the characteristics of a diaphragm spring clutch to a particular application, and it had not been possible to use a diaphragm spring clutch in certain high performance or high horsepower applications. Likewise, it had been impossible to similarly tailor a compression spring clutch to a particular application. Changing from a compression spring system to a diaphragm spring system had generally been prohibitively expensive because so many new parts had to be purchased. Also, such conversions were sometimes not available, or were of limited applicability. This inflexibility in clutch options tended to limit the usefulness and enjoyment of the motorcycles. Those concerned with these problems recognize the need for improvements.
These and other difficulties of the prior art have been overcome according to the present invention.